System and method for increasing the shear strength of a framed structure

ABSTRACT

Reinforcing system for retrofitting wall to increase the ductility and resistance to shear forces of a gypsum board wall to a level comparable to plywood-sheathed wall. Fiber-reinforced polymer panel is attached to substantially cover surface of gypsum board to protect it against rupture in earthquake. Reinforcement is enhanced by fiber anchors installed along base of wall and door frames. Connector strips tie together frame members to prevent separation from wall.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation-in-Part of co-pending applicationSer. No. 12/459013, filed Jun. 25, 2009, which is itself a C-I-P ofapplication Ser. No. 11/399,282, filed Apr. 6, 2006 and issued Aug. 18,2009 as U.S. Pat. No. 7,574,840; which is a C-I-P of application Ser.No. 10/205,294, filed Jul. 24, 2002 and issued Apr. 24, 2007 as U.S.Pat. No. 7,207,149. These previous applications are incorporated hereinby reference.

FIELD OF THE INVENTION

This invention relates in general to reinforcing a structure, and moreparticularly to increasing the shear resistance of an existing structurewith framed walls.

BACKGROUND OF THE INVENTION

Buildings have traditionally been designed to support their own weightplus that of expected inhabitants and furnishings. Buildings and otherstructures for supporting weight have long been expected to be verystrong under vertical compression. Concrete is a favorite material forweight-bearing structures because it is inexpensive and has exceptionalcompressive strength.

In the mid-1900s, architects began to take lateral forces into accountmore than they had previously. Wind can exert strong lateral force ontall buildings and long bridges. Smaller structures were still designedwithout much regard for strong lateral forces, though, until concern forearthquake resistance began growing in the 1970s in the United States,partly due to the massive Anchorage earthquake in 1964.

Frame structures consist of a skeleton of elongate wood, metal, orconcrete members that are connected together. These elongate members maybe connected together by various means. In some cases brackets that joinelongate members while resisting twist are used. More typically, framingmembers are connected with nails or screws that are easily bent and thatcan allow the framing members to pivot about the connection when understress from an unusual direction.

Many modern buildings, including most residences, are supported by aframework consisting of an array of vertical support members connectedat top and bottom by horizontal connecting members. The most familiarexample of this type of construction in the United States is the woodenframe house with 2×4 inch wooden studs connected by a wooden bottomplate at the bottom and a wooden top plate at the top.

The bottom plate connects the frame to the foundation and the top plateconnects to the roof The studs are typically attached to the top andbottom plates by stiff attachment means such as nails or screws. Thewooden framework provides the compressive strength sufficient to supportthe weight of the walls and roof. However, a conventional woodenframework does not have much resistance to the lateral forces that mayresult from earthquake or high wind.

Typically, a degree of shear bracing is added in the form of somediagonal “let-in” braces added between vertical studs. The braces are toprevent twisting of the framed structure, such as could be caused bywarping of the studs or plates as the wood reacts to varying temperatureand humidity conditions. Horizontal blocking members are attachedbetween studs for various reasons, such as to increase the stiffness ofa wall where cabinets will be attached or to maintain lengthy studsparallel to each other.

Once the framework skeleton is complete, a sheathing of some material isapplied over the framing to give a smooth surface and to increase theshear resistance of the wall. Such a sheathing material is typicallyplaster, wood paneling including plywood, or gypsum board, also known asdrywall or sheetrock.

The stiffness of the sheathing material helps maintain the frameworkerect under lateral forces such as earthquake or high wind. Buildingcodes take this effect into account and allow designers to include fewerdiagonal braces or other shear reinforcements than would be required forunsheathed frame walls. Because various sheathing materials are known tohave different shear strength values, there are different coderequirements for constructing the frame, depending upon the plannedsheathing material.

The shear strength values were formerly derived from small scalemechanical tests of the materials themselves. Testing of constructionmaterials has become more realistic and sophisticated in the past fewdecades. As a result, some of the previously used strength values havebeen found to be inaccurate.

In particular, buildings that use gypsum board for interior walls, alsocalled drywall construction, have been found to have much lessresistance to lateral forces than their designers intended. For manyyears, designers used an erroneously high value for the shear resistanceof walls faced with gypsum board. Later research, as well as analysis ofbuildings damaged by earthquake or wind, has shown that the true shearresistance contribution of gypsum board is only about 10% of what waspreviously accepted.

Many buildings worldwide need to be retrofitted so as to have thedesired degree of shear force resistance. A conventional method forstrengthening such buildings is to pull out the gypsum board and replaceit with plywood that is attached to the building framework.

Replacing gypsum board with plywood is an effective method forincreasing the resistance to lateral forces, but has disadvantages. The“demolition” step of removing the gypsum is extremely dusty, releasingparticles into the atmosphere of the building and generating largerparticles that drop to flat surfaces and into crevices. Between disposalof the bulk of the gypsum board and the cleanup of the building, a greatdeal of solid waste is created.

The dust may include gypsum, asbestos, and paper. Because dust in theair is harmful to people, animals, and many machines, the contents ofthe building have to be wrapped, packed, or removed so they are notcontaminated. Residents or workers in the building being retrofitted maybe required to absent the building for a day or longer.

Both the steps of demolition and of installing plywood are noisy for theentire duration of the work. Even if people and machines in the buildingcan be isolated from the dust by temporary walls, such as of plasticsheeting, it is likely that the noise of the operation would preventoccupants from working or resting in the building during theretrofitting.

Simply replacing the drywall sheathing of interior walls with plywoodmay not be enough to increase the strength of the structure as much asdesired. Additional wooden bracing within the walls or use of metal tiestraps to connect various components of the structure together may beneeded.

To withstand lateral forces such as seismic or wind forces, astructure's components must be strongly connected together. Yet, it hasbeen found that extremely rigid structures do not fare as well inearthquakes or wind as structures with some flexibility. Replacinggypsum board with nailed-in plywood does not significantly improve theductility of the structure. If additional internal bracing or metalconnectors must be installed, the ductility of the structure may beactually reduced, leaving the structure still vulnerable to cracking orrupturing under strong lateral force. A violent failure of one componentof a structure often causes a sudden chain reaction failure of othercomponents, possibly trapping or crushing occupants. A ductile structureis more likely to fail in a gradual manner, allowing time for occupantsto notice the impending failure and take steps to evacuate or evenrepair damage.

Seismic retrofitting by replacing gypsum board with plywood is expensiveand is therefore typically being done on only the highest-riskstructures. Costs of the method include loss of productivity and use ofthe building during the retrofitting, potential cost of temporarilyrelocating occupants, dust abatement and cleanup, cost of demolitionlabor and disposal fees for the gypsum, cost of protecting contents ofthe building, cost of additional bracing and reinforcing, and cost ofthe plywood itself and its installation. Lastly, after the walls arereplaced, paint, trim, wallpaper and other ornamental finishes must bereplaced.

The need for a less costly method of seismic retrofitting of drywallstructures is great. Such a method should provide shear resistance thatis at least equivalent to that of plywood. There is a need for such aretrofit method that does not generate large quantities of solid wasteand that does not contaminate the structure with harmful dust andparticles.

There is further a need for a retrofit method that can be performedwhile people work or live in the building, without undue noise orexposure to harmful materials. Such a retrofit method should preferablymake it more likely that any failure of the structure, if it does occur,is gradual instead of sudden and catastrophic so that occupants mayescape.

SUMMARY OF THE INVENTION

The present invention is a system for increasing the shear resistance ofgypsum sheathed walls and reinforcing the attachment among multiplestructural components. A structure reinforced by the materials andmethod of the invention is less likely to fail under lateral forces,such as those experienced during an earthquake, hurricane, or explosion.

The resistance to shear forces of structures reinforced by the system ofthe present invention is at least as great as that of structuresreinforced by the conventional replacement of gypsum with plywood.However, the apparent ductility of the structure is greater and thetotal cost is significantly lower.

Using the system of the present invention, retrofitting can be performedwhile people occupy the building, without creation of dust and with muchless noise than is made during the conventional procedure. Much lesssolid waste material is created.

The method of the present invention includes covering gypsum wallboardwith thin composite sheeting, such as panels or strips ofpolymer-impregnated textile. Ductile attachment means, preferably fiberanchors as disclosed in U.S. Pat. No. 7,207,149, are installed toconnect the covered wall to an adjacent structural component such as aconcrete slab or frame member.

If connecting straps are needed for additional connection amongstructural components such as door frames or between floors ofmultilevel buildings, long strips of composite are applied where neededon the outer surface of the gypsum wallboard. No bracing inside of thewall is necessary and the gypsum board remains in place throughout thestructure.

This method is fairly quiet and dustless, so therefore does not requirerelocation or protection of occupants and equipment. The compositepanels used contain only small amounts of volatile chemicals, so thereis no hazardous or intrusive odor. Because the gypsum wall sheathingremains in place, a large quantity of solid waste is not generated andthe retrofitting is completed in less time.

The system and method of the present invention provides a lower-cost,safer, and faster alternative to replacement of gypsum board withplywood, yet improves the shear strength of the retrofitted building atleast as well as the plywood replacement method.

The invention will now be described in more particular detail withrespect to the accompanying drawings, in which like reference numeralsrefer to like parts throughout. In the drawings, not all details ofconstruction of the structures are shown, for the sake of clarity.However, the illustrated structures are intended to representconventional structures that include framed walls with brittle wallsheathing, such as gypsum board.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevation view, cut away, of a first embodiment of thereinforcement system of the present invention reinforcing a conventionalframe and gypsum board wall.

FIG. 2 is a front elevation view, cut away, of a second embodiment ofthe reinforcement system of the present invention reinforcing a wallthat includes other structural elements, namely door frames.

FIG. 3 is a front elevation view of a third embodiment of thereinforcement system of the present invention reinforcing a wall byreinforcing the connection among framing members.

FIG. 4 is an enlarged view of the upper right portion of FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a front elevation view of reinforcement system 10 of thepresent invention reinforcing a portion of a structure 100, such asconventional frame wall 110 that is covered with a sheathing of gypsumboard 112, which is partly cut away. Frame wall 110 includes framingmembers 115, vertical and horizontal members, typically of wood. Gypsumboard 112 is nailed to framing members 115 to cover framing members 115and give wall 110 a smooth outer surface 113. Wall 110 is supported by afoundation, such as concrete slab 130.

Reinforcement system 10 as shown in FIG. 1 includes a sheet of textile20, such as fabric that is woven or knit from fibers with high tensilestrength. Textile 20 is stretched over surface 113 of gypsum board 112and attached by suitable means, such as adhesive. Adhesive may bepreviously applied to surface 113 before textile 20 is stretched oversurface 113, or textile 20 may be stretched and temporarily attached,such as with staples, then adhesive may be sprayed or rolled on overtextile 20 to attach textile 20 to surface 113.

Preferably, textile 20 is a panel of fabric that is pre-impregnated withsynthetic resin, such as epoxy, urethane, or other polymers as arewell-known in the art. Most preferably, the impregnation step has beenperformed at another location and most solvents or other volatilecomponents of the resin have already evaporated. The “B-stage” gel thatremains in textile 20 thus has low odor and low human toxicity viarespiration. The B-stage panel of textile 20 is flexible and easy tocut, drill, or punch, but is not so sticky that it is difficult tohandle.

This type of textile panel is commonly known as “pre-preg” or “FRP”(fiber-reinforced polymer). The fiber portion of the panel is typicallywoven or knitted filaments of glass or graphite carbon. A suitable FRPpanel typically is tacky enough to adhere lightly to a wall uponcontact, then cures at ambient temperature over a period of hours ordays to become tightly adhered. Such a panel may also be applied to aceiling, but may require an additional tack coat of liquid or pastyadhesive to hold it in place during curing. Light mechanical fastenerssuch as staples may also be used.

If textile 20 is not pre-impregnated with resin, various means forattaching textile 20 to wall 110, as are known in the art, may be used.For example, textile 20 may be run between rollers that apply a suitableadhesive. Alternatively, textile 20 may be stretched over surface 113then suitable adhesive is applied over textile 20 such as by brush orspray. The adhesive will penetrate textile 20 and adhere to surface 113.

Examples of suitable adhesives include epoxy, polyurethane, latex, andacrylic. It is preferred that the adhesive used should be low involatile emissions during curing and that any vapors emitted be lowtoxicity and low odor.

For maximum improvement of ductility and strength, textile 20 isattached to wall 110 substantially coplanar, so as to largely cover wall110. That is, textile 20 is not attached to wall 110 such as by edgesonly or by intermittent areas of adhesive. Textile 20 is preferablyattached across its entire wall-facing surface to surface 113 of wall110.

Fiber anchors 30, as are known in the art and disclosed in U.S. Pat. No.7,207,149, are installed along one or more edges of wall 110. Boreholes31 are drilled into an anchor medium adjacent wall 110, such as intoslab 130, into the soil supporting structure 100, or into a frame member115 of wall 110 or a frame member 115 of an adjacent floor or level ofstructure 100.

Boreholes 31 are typically drilled into a framing member 115 near thetop or bottom of wall 110. However, a borehole 31 can optionally bedrilled through gypsum board 112 and into an underlying framing member115 in order to install a fiber anchor 30 that is not disposed at anedge of wall 110.

A length of roving 32, composed of loosely twisted filaments of ductile,strong fiber, is inserted into each borehole 31 with a free end 33protruding. Free end 33 of roving 32 is splayed out against textile 20and attached to textile 20 with a suitable adhesive 36.

One preferred method of practicing the invention is to first attachtextile 20 to surface 113, then to attach free end 33 over textile 20such that free end 33 is attached with adhesive 36 to the outer surfaceof textile 20. A second preferred method of practicing the invention isto attach free end 33 directly to surface 113 of wall 110, then toattach textile 20 with adhesive such that free end 33 is attached to theinner surface of textile 20.

In the exemplary embodiment of FIG. 1, a plurality of fiber anchors 30are shown as arrayed along the sill of wall 110 with boreholes 31drilled into slab 130. The combination of textile 20 and fiber anchors30 provide a strong ductile connection between slab 130 and wall 110,reinforcing wall 110 against being disconnected from slab 130 by stronglateral force, such as from an earthquake. Perhaps more importantly,textile 20 increases the ductility of surface 113 of wall 110, makinggypsum board 112 unlikely to rupture catastrophically.

To reinforce connection among floors of a structure, anchors 30 may beinstalled such that borehole 31 is drilled into a frame member 115 of anadjacent floor. For example, borehole 31 may be drilled upwardly into asupport member 115 of the floor above. In this case, free end 33 wouldextend downward and be splayed against an upper portion of surface 113of wall 110.

It is also within the scope of the present invention to drill borehole31 through an adjacent frame member 115, such as a joist or beam, andinsert roving 32 through borehole 31 such that a free end 33 protrudesfrom each end of borehole 31. A first free end 31 is splayed andattached to a first wall, ceiling, or floor; and a second free end 31 issplayed and attached to a second wall, ceiling, or floor.

From observing the effects of actual strong earthquakes and simulatedearthquake tests on conventional structures 100, non-reinforced gypsumboard 112 has been found to respond in a brittle manner, cracking andrupturing away from framing members 115. Once gypsum board 112 ruptures,it contributes no strength to wall 100, allowing framing members 115 tobend their connections, typically nails, screws, or brackets, so as toallow wall 100 to collapse. This type of failure in one section of wall110 may lead to further failures in other sections of structure 100.

Reinforcement system 10 of the present invention increases the ductilityof wall 110 and connects wall 110 to the foundation, such as slab 130 ora lower floor (not shown) of structure 100, in a strong ductile manner.Even under strong lateral forces, such as from a major earthquake,reinforced structure 100 maintains connection among all components suchas framing members 115, gypsum board 112, and slab 130. As long as allthe components of structure 100 remain connected, they act cooperativelyto maintain structure 100 in a non-collapsed state, even if some lesserdamage such as breaking of windows occurs. It has been found inlaboratory testing that reinforced gypsum board 112 may crack, butbecause it is supported against rupture by textile 20, gypsum board 112remains attached to framing members 115 and does not fully break orcollapse.

FIG. 2 is a front elevation view of a second embodiment of reinforcementsystem 10 of the present invention reinforcing a wall 110 that includesother visible structural elements, namely door frames 120 or windowframes. Wall 110 is sheathed by gypsum board 112 and is reinforced withtextile 20, shown partly cut away, and fiber anchors 30 of the typepreviously discussed.

Some structures 100 may need further reinforcement among individualcomponents, such as connecting door frames 120 to reinforced wall 110 toprevent them from separating from wall 110 and toppling to one side orthe other of wall 100 under strong lateral forces. In the past, peoplewere advised to take refuge in a doorway during a strong earthquake andmany people still do this. Thus, it is especially desirable that doorframes 120 not separate from wall 110, possibly injuring a person tryingto shelter in the door opening.

In conventional structures 100 that experience strong lateral forces,especially forces that change direction such as earthquakes, certainstructural components such as door frames 120 may sway with a differentfrequency than the sway frequency of the rest of wall 110 or structure100. The unsynchronized swaying may cause gypsum board 112 around doorframes 120 to crack or rupture, allowing door frames 120 to separatefrom wall 110 and possibly topple away from wall 110.

To further reinforce structural components that are not stronglyconnected to the rest of structure 100, such as door frames 120, long“drag” or “collector” strips 40 of textile 20 connect a plurality ofdoor frames 120. As shown in FIG. 2, each door frame has two verticalcollector strips 40 attached generally over or in proximity to thevertical members of the door frame 120. A long horizontal collectorstrip 40 is attached above door frames 120; horizontal strip 40 isattached with a suitable adhesive to surface 113 and to the verticalcollector strips 40. The adhesive used to attach connector strips 40 maybe the same as used to attach textile 20, but different adhesive mayalso be used. Collector strips 40 may alternatively be additionallyattached to framing members 115 with mechanical fasteners, such asscrews (not shown) to further increase the strength of the structure.

Drag, or collector, strips 40 provide strong ductile connection amongdoor frames 120 and connect door frames 120 to other structuralcomponents, such as wall 110. In the event of a major earthquake orother strong lateral force, such as from a hurricane or explosion, doorframes 120 will sway in unison with framing members 115 and reinforcedgypsum board 112 instead of breaking away from them.

In like manner, collector strips 40 may be employed to reinforce theconnection among many structural components, including but not limitedto doors, windows, tilt-up walls, chimneys, and balconies. Collectorstrips 40 are not always required, but may be optionally employed tomeet the requirements of a given application.

Collector strips 40 are optionally used to create a load path amongfloors or other portions of a structure 100. A slot may be cut, such asthrough a ceiling or floor, to allow a collector strip 40 to be passedthrough. Collector strip 40 is then attached by suitable adhesive tosurfaces 113 of walls 110 on different floors of structure 100, or toframing members 115 or other components of structure 100, asappropriate. For creating a load path through structure 110, collectorstrip may be oriented vertically, horizontally, or at an angle.

Another preferred use of collector strips 40 is to buttress theattachment of fiber anchors 30 to surface 113, as seen in the middleportion of FIG. 2. An elongate collector strip 40 about 12 inches widemay be placed over a plurality of anchors 30, whether anchors 30 aredisposed along the bottom or the top of wall 110.

FIG. 3 is a front elevation view of a third preferred embodiment ofreinforcement system 10 of the present invention reinforcing a wall 110by reinforcing the connection among frame members 115. FIG. 4 is anenlarged view of the upper right portion of FIG. 3.

Frame members 115 for one wall 110 typically are rigidly joined so as toform a structural element that has good compressive strength and goodflatness, but does not typically have good resistance to forces normalto the plane defined by wall 110. Frequently, especially in olderstructures, a framed wall is supported against normal forces mainly bythe attachment of other, non-parallel walls. The framed wall may nothave sufficient integrity to remain upright when stressed by a largelateral force and the main section will frequently tear apart from therigidly attached corners.

Reinforcement system 10 of the present invention increases the ductilityof the framed wall and spreads forces throughout the framed wall 100.This allows the framed wall to retain integrity along its entire lengthwhen stressed laterally and to remain connected to adjacent walls,foundation 120, and roof. Framed wall 100 typically includes at leasttwo vertical support members 102 such as first stud 103 and second stud104; and horizontal connecting members 105 connecting the ends of studs103,104 such as top plate 106 connecting the top ends of studs 103,104and bottom plate 107 connecting the bottom ends of studs 103, 104.Bottom plate 107 is also connected to foundation 120. Framed wall 100also includes wall sheathing 110, such as of gypsum board 112.

As shown in the drawings, reinforcement system 10 provides ductileconnections among top plate, bottom plate, and vertical studs of thewooden framing behind wall. At least one collector strip 40 is attachedto wall such that top end 41 is over top plate, bottom end 42 is overbottom plate, and the middle portion crosses over one or more verticalstuds. Top end 41 and bottom end 42 are attached to their respectiveplates by ductile means, preferably fiber anchors 30.

Each FRP strip 12 includes a first end 13, a second end 14, and a middleportion 15 between ends 13,14. Each FRP strip 12 further includes aninner face 17 that is attached to wall 100 and an exposed face 18,opposite inner face 17, and which faces away from wall 100.

FRP strips 12 are typically attached in pairs, preferably forming an “X”upon a section of framed wall 100. FRP strips 12 may be attached overexisting wall sheathing 110 or directly on bare framing members 101 in astructure being built or remodeled.

It has been found through experimentation that reinforcement system 10is strongest if FRP strips 12 are attached such that the longitudinalaxis of one strip 12 of a pair is at an angle of nominally 90° to thelongitudinal axis of the other strip 12 of the pair. Thus, thehorizontal width of the “X” should be about equal to the verticaldistance from bottom connecting member 107 to top connecting member 106.

Because ends 13,14 of FRP strips 12 are attached over a junction 109,that is, to both a vertical support member 102 and a horizontalconnecting member 105, the width of the “X” will actually be a multipleof the spacing of support members 102. For this reason, FRP strips 12cannot always be at a 90° angle to each other, but care should be takento set up reinforcement system 10 to come as close as possible to thepreferred angle of 90°.

FRP strips 12 may be precut to a length determined to yield a “X” ofappropriate dimensions, or FRP strips 12 may be cut as they are usedfrom a length or roll of FRP material 12.

It is convenient to attach ends 13,14 to frame members 101 initiallywith some temporary means, such as staples. Then ends 13,14 are attachedpermanently by ductile attachment means 30, such as a plurality of fiberanchors 32.

Each end 13,14 is attached to both a vertical support member 102 and ahorizontal connecting member 105. To accomplish this, end 13,14 isattached so as to generally cover junction 109 where a vertical supportmember 102 and a horizontal connecting member 105 abut.

For example, in FIG. 1, first end 13 of first strip 12 a is attached toboth first vertical support 103 and top connecting member 106. First end13 partially covers junction 109 surrounding the area where firstvertical support 103 and top connecting member 106 contact each other.

To create each fiber anchor 32, a borehole 34 is created, which passesthrough an end 13 or 14 of FRP strip 12 and into a frame member 101,underneath end 13 or 14. Precut FRP strips 12 may include pre-punchedholes at appropriate locations in ends 13,14. In this case, an electricdrill would be inserted into a punched hole and borehole 34 finished bydrilling about an inch into the wood of frame member 101. Alternatively,borehole 34 may be drilled directly through end 13 or 14 and into framemember 101.

Each fiber anchor 32 so created attaches end 13,14 to one of theunderlying frame members, 102,105. Each end 13,14 is preferably attachedwith a plurality of fiber anchors 32. Fiber anchors 32 are disposed suchthat some anchors 32 attach a given end 13, 14 to vertical supportmember 102 and some anchors 32 attach the same end 13, 14 to thehorizontal connecting member 105 near junction 109 where the two framemembers 102,105 abut. Thus, the plurality of fiber anchors 32 ductilelyattach each end 13 or 14 to both a vertical support member 102 and ahorizontal connecting member 105, and indirectly reinforce theattachment of the two members 102,105 to each other.

Middle portion 15 of each FRP strip 12 is attached to wall sheathing 110by adhesive means, such as the resin that impregnates FRP strip 12. Thisresin may be a partially cured (“gelled” or “B-staged”) resin that issupplied as a component of FRP strip 12, or liquid resin that is appliedat the worksite, such as by dipping a strip 11 into a container ofresin, or by rolling or brushing resin over strip 11 that has beenattached to wall 100 by temporary means or with ductile attachment.

The most preferred manner of practicing the reinforcement system 10 ofthe present invention, as illustrated in the drawings, is to furtherattach an anchor plate 20 to each junction of vertical support member102 and horizontal connecting member 105 to which first end 13 or secondend 14 will be attached.

Referring especially now to FIG. 1, anchor plates 20 are generallysquare plates, such as of wood or plastic. For use in a single-familyhouse, typical dimensions are 12 by 12 inches with a thickness of about0.25 inch.

The purpose of anchor plates 20 is to spread out forces. Because eachanchor plate 20 is connected to both a vertical support member 102 and ahorizontal connecting member 105, each fiber anchor 32 is effectivelyconnected to both members 102,105 as well. Anchor plate 20 helpsstabilize fiber anchors 32 such that each fiber anchor 32 helpsreinforce against forces from any direction. Anchor plate 20 also helpsensure that fiber anchor 32 will not pull out under especially violentforces.

System 10 of the present invention is described herein as being usefulfor reinforcing walls that are covered, or sheathed, with gypsum board112, often known as drywall or sheetrock. While there are very manygypsum board walls urgently in need of reinforcement, there are alsoother types of structural components that can be reinforced using system10. For example, reinforcement system 10 may be used to strengthen wallsthat are sheathed with plywood, if a very strong and ductile wall isrequired. Reinforcement system 10 is most simply applied to planarsurfaces, such as wall 110 described herein, but may be employed toconnect walls that are at an angle to each other, including both“inside” and “outside” right angles.

Although particular embodiments of the invention have been illustratedand described, various changes may be made in the form, composition,construction, and arrangement of the parts herein without sacrificingany of its advantages. Therefore, it is to be understood that all matterherein is to be interpreted as illustrative and not in any limitingsense, and it is intended to cover in the appended claims suchmodifications as come within the true spirit and scope of the invention.

1. A system for reinforcing a framed structure, the structure including:a plurality of framing members including: at least one pair of verticalsupport members in parallel spaced-apart relation, one horizontal topconnecting member connecting the top portions of the vertical supportmembers, at least one horizontal bottom connecting member connecting thebottom portions of the vertical support members and wall sheathingattached over the framing members; said system including: at least oneconnector strip of resin-impregnated textile, said strip adapted toconnect a top connecting member to a bottom connecting member; saidstrip including: a first end attached to the top connecting member; asecond end attached to the bottom connecting member; an inner facedisposed toward the wall sheathing; an exposed face disposed away fromthe wall sheathing; and a middle portion between said first and secondends; and ductile attachment means attaching each said end to oneconnecting member.
 2. The system of claim 1, further including: at leastone anchor plate, said anchor plate attached between one said strip endand one connecting member; said ductile attachment means furtherattaching said anchor plate with said strip end and said connectingmember.
 3. The system of claim 1, said at least one connector stripcomprising: a pair of connector strips attached to the top and bottomconnecting members such that said pair of connector strips form an “X”shape on the wall sheathing.
 4. The system of claim 3, said pair ofstrips attached such that the longitudinal axis of one said strip isdisposed at a angle in the range of 70-110 degrees to the longitudinalaxis of the other said strip.
 5. A method for reinforcing a framedstructure that includes framing members, including a first verticalsupport member and a second vertical support member in parallelspaced-apart relation, one horizontal top connecting member connectingthe top portions of the vertical support members, and at least onehorizontal bottom connecting member connecting the bottom portions ofthe vertical support members; the method including the steps of:providing a first strip of material having: a first end, a second end,and a middle portion therebetween and with a length approximating thedistance between the junction of the first support member with the topconnecting member and the junction of the second support member with thebottom connecting member; attaching the first end of the first strip tothe junction of the first support member with the top connecting memberusing ductile attachment means; attaching the second end of the firststrip to the junction of the second support member with the bottomconnecting member using ductile attachment means; providing a secondstrip of material having: a first end, a second end, and a middleportion therebetween and with a length approximating the distancebetween the junction of the second support member with the topconnecting member and the junction of the first support member with thetop connecting member; attaching the first end of the second strip tothe junction of the second support member with the top connecting memberusing ductile attachment means; and attaching the second end of thesecond strip to the junction of the first support member with the bottomconnecting member using ductile attachment means such that the middleportion of the second strip overlies the middle portion of the firststrip.
 6. The method of claim 5, wherein the ends of the strips ofmaterial are attached to junctions of framing members such that thelongitudinal axes of the attached first and second strips form an angleof 70 to 110 degrees.
 7. The method of claim 5, wherein each step ofattaching an end of a strip to a junction using ductile attachment meanscomprises the step of creating a fiber anchor, further including thesub-steps of: creating a borehole that passes through the end of thestrip and into a framing member; inserting a length of roving throughthe end of the strip and into the framing member such that a free endprotrudes from the end of the strip; backfilling the borehole withadhesive to capture the roving; and attaching the free end of roving tothe end of the strip with adhesive.
 8. The method of claim 7, whereineach step of attaching an end of a strip to a junction comprises thestep of creating a plurality of fiber anchors by repeating the sub-stepsof claims 7 a plurality of times.